Cisco Systems 7920 manuale d’uso

Corporate He adquarters Cisc o Syst ems , Inc . 170 West Ta sman Drive San Jos e, CA 95 134-1706 USA http://www.ci sco.com Tel: 408 526-4000 800 553- NETS (638 7) Fax: 408 526-4100 Site Sur v e y Guide f or Deplo ying Cisco 7920 IP Phones April 20 05 Text Pa rt Nu mber: OL-6315- 01[...]

THE SPECIFICATIONS AND INFORMATION REGARDING TH E PRODUCTS IN THIS MANUAL ARE SUBJE CT TO CHANGE WITHOUT NO TICE. ALL STATEMENT S, INFORMATI ON, AND RECOMMENDA TIONS IN T HIS MANUAL ARE BELIEVED TO BE ACCURATE BU T ARE PRESEN TED WITHOUT WARRANTY OF ANY KIND, EXPRE SS OR IMPLIED. USERS MUST TA KE FULL RESPONSIBILITY FOR THEIR AP PLICATION OF ANY PR[...]

iii Site Sur vey Guide fo r Deploying C isco 7920 IP Pho nes OL-6315-01 CONTENTS Preface v CHAPTER 1 Overview 1- 1 Recommenda tion s for Succe ssful VoI P Surveys 1-1 Gettin g star ted 1-2 Minimum Requ irement s for WIPT Cel ls 1-4 The Idea l WIPT Env ironment 1-5 Data Ra te a nd Sign al S trength Cons iderati ons 1-6 Mult i-floo r surv ey 1-7 Comp[...]

Cont ent s iv Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01[...]

v Site Sur vey Guide fo r Deploying C isco 7920 IP Pho nes OL-6315-01 Preface This doc ument provides inst ructio ns and guidelin es for condu cting a site su rvey for wir eless LA Ns using V oice over IP (V oIP) o n Cis co 79 20 IP Phon es. W ith the intro ducti on of voice to a predom inantl y wireless da ta network the method ology of site surve[...]

vi Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Preface[...]

C HAPTER 1-1 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 1 Overview This documen t be gins by identif ying the spec ific radi o en vironmenta l v alue s that ar e ne eded fo r a successful voice de ployment. Note Cisc o offers a Cisco Aironet Wireless Site Survey class for techni cal individuals who w ill be perf orming site[...]

1-2 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Ch apter 1 Over vi ew Recomme ndations for Success ful VoIP Survey s degr adation. This qua lity requiremen t also dictates the need for a fast roami ng solution betwee n access points whe re the network can re associate a client to a new access point with in 100 ms (that is, wit[...]

1-3 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 1 Ov erview Recommen dations f or Succ essful Vo IP Surveys Figur e 1 -1 ACU Site Surv e y Window Noise is def ined as a 2.4-GHz signal that is not in an 802 .11 DSSS format bu t is in the frequency range of the access p oint’s conf igure d ch anne l. The noise can or[...]

1-4 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Ch apter 1 Over vi ew Recomme ndations for Success ful VoIP Survey s Figur e 1 -2 Signal to Noise Ratio Minimum Require ments for WIP T Cells Ta b l e 1 - 1 lists the minimum v alues for v oice and data cells. F or WIPT cells, Cisco recommend s that the cell edg e be –67 dBm a [...]

1-5 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 1 Ov erview Recommen dations f or Succ essful Vo IP Surveys difference in transm itter power an d receiver sensitivity that ma tters beca use the gai n of an an tenna i s recip rocal. T o v erify the ce ll coverage ed ge of –67 d Bm whi le the client is actively sendi[...]

1-6 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Ch apter 1 Over vi ew Recomme ndations for Success ful VoIP Survey s Figure 1-4 also illustrates the recommended o ver lap of 15 to 20 percent for WIPT cells ( larger than the 10 to 15 p ercent for data cells). The reason for the increa se in o verla p is to pro vide en ough capa[...]

1-7 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 1 Ov erview Recommen dations f or Succ essful Vo IP Surveys The char acteristic s of V oIP r equire a met iculous WIPT site sur vey . T o av oid a c all with ji tter , th e delay variation betwe en packets shoul d not exceed 30 ms. Th e one-way de lay should not exceed [...]

1-8 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Ch apter 1 Over vi ew Recomme ndations for Success ful VoIP Survey s Compariso n of a M anual Surve y and an A utomated S urvey Figure 1-6 sh ows an act ual ho spital survey done using Ai rMag net Surveyor wit h an 8 02.11b Cisco PCM350 cl ient ca rd. Four pa nels on t he Ai rMag[...]

1-9 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 1 Ov erview Recommen dations f or Succ essful Vo IP Surveys Fi g u re 1-7 Ho s p i ta l F l oo r Su r vey by a S u r vey Cre w[...]

1-10 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Ch apter 1 Over vi ew Recomme ndations for Success ful VoIP Survey s[...]

C HAPTER 2-1 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 2 Survey Tools AirM agnet offers ma ny tools f or an alyzi ng 80 2.11 perform ance at a site . Fi gure 2-1 sh ows the AirMagn et Survey tool. Cisco reco mmend s AirMagne t for data an d WIPT surveys. Figur e 2-1 AirMagne t Surve y T ool An acc urate s urv ey requi res [...]

2-2 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls Figur e 2-2 AirMagnet P a ck et Decode T ool The 7920 survey tool rep orts the signal stren gth of the sign al from the a ccess poi nt as an RSSI value. Most client c ard utilitie s report signal str ength as dBm or per cent of signal str ength. In this c[...]

2-3 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools The d ata in Ta b l e 2 - 1 was c reated fr om live tests. Each tool an d card combi nation data po int was taken at the sam e time from the same dis tance. Th e en viro nment w as an open of fice . The fl oor plan used for the test is sho wn in Figure 2-[...]

2-4 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls The Cisc o CB21 ADU repor ts signal st rength in dBm . Figur e 2-4 shows the ADU Adv anced Status windo w . Figur e 2-4 ADU Ad v anced Stat us Windo w[...]

2-5 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools Figur e 2-5 AirMagnet Surve y T ool[...]

2-6 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls The Air Magnet Survey packet de code tool shows signal strengt h in dBm. Figur e 2-6 shows the AirMag net Surv ey P acket Decode win do w . Figur e 2-6 AirMagnet P a ck et Decode Windo w The AiroPeek tr ace sho ws the signal dBm v alue and signal percenta[...]

2-7 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools Figur e 2-7 Air oP eek Windo w AiroPeek has options to show real-t ime graphs of current signal strengt h and current noise le vels both in dBm and pe rcen tages, but it does not have a surve y tool like A CU or AirM agne t. Figure 2-8 shows the AiroPeek [...]

2-8 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls Figur e 2-8 Air oP eek dBm and Signa l P er centag e Real-Time Graph s Snif fer Pro fr om Network A ssociates sho ws th e signal strength in a perce nt v alue. There is no option to sho w RSSI or dBm v alues. Snif fer Pro is t race utility with no support[...]

2-9 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools The Cisc o access point displ ays the signa l strength of the packets fr om the client. The signal str ength of the ac cess point as r eported b y the client utilit y should be relati v ely close to t he signal stre ngth reported by the access point for t[...]

2-10 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls Figure 2-11 shows that the 7920 hears th ree acce ss points an d the RSSI values of those access points ar e 18, 31, and 48. Figur e 2-1 1 Cisco 79 20 IP Phone Surv ey Scr een Y ou can also use Air Magnet Su rveyor to de termine chann el s eparation. Fig[...]

2-11 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools Survey Too ls for Pa cket Jit ter Survey Tools for Packet Jitter T ypicall y , voice pac kets ar e sent every 20 ms. V oice calls ar e usual ly bursty , co nsist ing of a group of tightly pack ed packet s in a transmit direction follo wed by a tigh tly p[...]

2-12 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls Survey To ols for Packet J itter Figur e 2-1 4 AirMagnet Jit te r T ool in an Ent er pr ise Off ice with High 8 02.1 1 T ra ffic Figure 2-15 an d Figure 2 -16 show the L iv eCaptu re window a nd the Station window re sults in a h ome off ice wit h low 80[...]

2-13 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 2 Survey Tools Survey Too ls for Pa cket Jit ter Home off ice u tiliz ation is 2 .18 p ercent and t he throughp ut i s 246 kbps for 1 1 Mbp s-onl y calls, wit h a single act iv e WIPT call, but utiliz ation is 15.41 perc ent with throughpu t of 248 kbps for 1 Mbps-onl [...]

2-14 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 2 Su rvey Too ls Survey To ols for Packet J itter[...]

C HAPTER 3-1 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 3 Surveying for Cell Capacity an d Channel Re-Use This chap ter de scribe s ho w to perfo rm a site sur ve y to de sign a wirele ss LAN for cel l capaci ty and chan nel re -use. Survey Design f or Cell Capacity Cisco recommends that you install enough access points to [...]

3-2 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapt er 3 Surveying f or Cell Capacit y and Channel Re -Use Survey Des ign for Cell Capac ity Note If the Cisco acces s point is configured to di sable data rates 1, 2, and 5. 5, clients ar e not requi red to transmit on ly at 11 Mbps. In fact, ol der cli ent devices might not b[...]

C HAPTER 4-3 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 4 Conducting a WIPT Survey This chapter describes specific steps for performing a site survey for WIPT . How To Survey for the WIPT Cisco recommen ds that the fi rst step of a surve y is to work wit h administrators at the local site to determ ine the requi rement s of[...]

4-4 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 4 C onducting a WIP T Survey How To Surve y for the WIPT Figur e 4-1 Ideal WIPT En vir onment Channel R e-Use Figure 4-2 shows the typica l chan nel r e-use fo r 802.1 1b and 802.1 1g WLAN s. The two gold chan nel 1 cells a re -8 6 dBm apart from ce nter to cente r . The [...]

4-5 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 4 Condu cting a WIPT Surv ey How To Survey for the WIPT Manual Su rvey for the WIP T Y o u can use passive or activ e mode w hen you use A CU to run a si te survey . Figur e 4-3 shows the A CU Site Surv ey windo ws. Figur e 4-3 ACU Site Surv e y Windows T o set u p acti[...]

4-6 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 4 C onducting a WIP T Survey How To Surve y for the WIPT Figur e 4-4 ACU Site Surv e y Activ e Mode Click OK to retu rn to the Site Surve y screen. Click Start to start the site surv ey in acti v e mode. This information updates constan tly during the surv ey: • Percent[...]

4-7 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 4 Condu cting a WIPT Surv ey How To Survey for the WIPT The AirMagnet su rve yor works v ery well for surv e ying a site with an in stalled WLAN or for surv e ying a site wit hout a WLAN. The tool w orks with the existing tra nsmit po wer of the a ccess points, b ut all[...]

4-8 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 4 C onducting a WIP T Survey How To Surve y for the WIPT Figur e 4-6 AirMagnet Surv e y Activ e Mode T o survey a group of acc ess point s using the A ctive Mode tool, configur e the too l with an SSID that is configured on the access points. T o be gin the data colle cti[...]

4-9 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 4 Condu cting a WIPT Surv ey How To Survey for the WIPT Figur e 4-7 AirMagnet Client W alkabout When you selec t display mode on the bottom tool bar, SiteV iewer displays da ta collec ted during t he surve y . T w o new panels appear in this mode: th e Filter area in th[...]

4-10 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 4 C onducting a WIP T Survey How To Surve y for the WIPT Figur e 4-8 AirMagnet Sho win g Acce ss P o ints and Mer g ed Displ ay Figure 4-9 sh ows Site V iewer’ s four-p anel display . V ie w ing more than one surve y data type helps you comp are me asure ment factor s.[...]

4-11 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 4 Condu cting a WIPT Surv ey How To Survey for the WIPT Figur e 4-9 AirMagnet Four -P anel Displa y[...]

4-12 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 4 C onducting a WIP T Survey How To Surve y for the WIPT[...]

C HAPTER 5-1 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 5 Positioning Access Points and Ante nnas for Site Surveys When you perform a site surve y , it is important to position wire less equipmen t for opti mal co verage. This chap ter de scribe s best practic es for p osition ing access p oints and antennas. Access Point P[...]

5-2 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 5 Positioning Access Points and Antennas for Site Surveys Antenn as and Ant enna Posit ioning The access point in Figure 5- 2 provides b etter c overage beca use the re flecte d sig nal prod uces fewer nul ls and less multipa th than the I-beam pl acement. Ho we v er , be[...]

5-3 Site Sur vey Guide fo r Deployin g Cisco 792 0 IP Phones OL-6315-01 Chapter 5 Positioning Access Po ints and A ntennas f or Site Surve ys Ant ennas an d Ante nna Pos itioni ng Figure 5-4 shows a p atch ante nna mount ed on a wa ll. The ant enna cab les are ro uted ab ov e the sus pende d ceili ng and are attach ed to a hi dden acc ess poi nt. F[...]

5-4 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Chapter 5 Positioning Access Points and Antennas for Site Surveys Antenn as and Ant enna Posit ioning Figure 5-6 shows a pat ch ant enna m ounted o n a suspe nded cei ling. The cable s are h idden an d are routed abov e the cei ling to the access point. Figur e 5-6 P atc h Ant en[...]

A- 1 Site Sur vey Guide fo r Deploying C isco 7920 IP Pho nes OL-6315-01 APPEND IX A Additional Sources of Information This a ppendix lists docume nts th at provi de addit ional i nfor mation about si te su rveys: • Cisco W ir eless IP Phone 7 920 D eploym ent Rec ommendat ions http://www .cisco.com/e n/US/products/hw/phon es/ps379/prod ucts_whit[...]

A- 2 Site Survey Guid e for Depl oying Cisco 7920 IP Phones OL-6315-01 Appendix A Additional Sources of Information[...]